D-18, D-28 … What it All Means

You walk into a music store to check out the latest in six string guitars that might be suitable for old-time music. You overhear the salesman talking to another customer and they seem to be talking in some cryptic code: “D-35, triple 0-18, M-36, D-28s.” Should you yell “Bingo!?” No, they are talking about different Martin guitar models.

Deciphering the Martin guitar code is simple. The model designations can be broken down into two parts. Take D-28, or 5-18 for example. The letter prefix “D” or number prefix “5” represents the guitar’s size. The suffix “28” or “18” indicates the type of materials used in building the guitar and the general ornamentation.

Martin guitars of the same prefix are all the same body size. The only differences are between the guitars with 12-and 14-fret necks. The older style necks had 12 frets. In the 1920s, guitarists developed more complex playing styles that necessitated access to the upper frets, and in 1929, Martin introduced the 14-fret neck. A guitar with a 14-fret neck has a body less than an inch shorter than a guitar with a 12-fret neck. All other dimensions are the same.

When I was a teenager, my family and friends played “D” or “dreadnaught” guitars, and this size has become a universal standard with its booming bass and powerful tone. It is the most copied guitar in the world.

These days I see more and more old-time musicians using smaller guitars. The size 5 is the smallest standard model that Martin has made in large quantity. Country music fans will recognize the guitar Marty Robbins used as a 5-18.

As the prefix numbers get smaller the guitars get bigger. After 5, come 4, 3, 2, and 1. Most of these sizes were made before World War II and are not common now, as most people prefer the tone and volume of larger guitars for group sessions.

Size “0” is the smallest of what most people consider a normal size guitar. They increase in size from 00, 000, D, M, to J. Martin even makes an acoustic bass guitar now with the prefix B. During the 1930s Martin also made archtop guitars with C, R, and F designations.

For the most part, the suffixes on Martin guitars go from low to high to indicate how fancy and what types of woods are used in construction. Here is a list and a brief description of the more popular styles:

15 – Mahogany top, back, and sides, with rosewood fingerboard and bridge. No binding on this model.

16 – A style introduced in the 1960s. Spruce top, mahogany back and sides, rosewood fretboard and bridge, dark binding on top.

17 – All-mahogany; similar to the style 15. In certain years they were made with bound tops and backs.

18 – Spruce top, mahogany back and sides, dark binding on top and back. Early models had ebony fretboards and bridges. Starting in the 1950s, the fretboards and bridges were made out of rosewood.

21 – Rosewood back and sides, spruce top, dark binding around the top and back. Fretboards and bridges were ebony until the 1950s when, like the style 18, they were replaced with rosewood.

28 -Probably the most popular of all Martin styles. Rosewood back and sides, spruce top. All Martin models 28 and above have ebony fretboards and bridges and are bound with white plastic. Models made before 1947 had the famed herringbone wood marquetry border around the top. In 1947 that top border was changed to alternating layers of thin black and white plastic. Herringbone trim was reintroduced by popular demand in 1976 with the production of the HD-28. The H stands for herringbone.

35 – Rosewood back and sides with spruce top. The special feature of this model is the 3-piece back. First made in 1965 to use smaller pieces of rosewood, 35s also have bound fretboards.

41 – Rosewood back and sides with spruce top. A fancy guitar, it has large abalone hexagon inlays on the bound fretboard, large “C. F. Martin” inlay made of mother of pearl or abalone in the headstock, and abalone trim around the body.

45 -The ultimate in standard-model Martin guitars. At a glance it looks like the 41, but close inspection reveals abalone trim not only on the top but on the back and sides as well. Also, the woods chosen for the 45s are of the highest grade.

I have covered all the standard models, but Martin has made many custom models. It would take a book to cover all of them, and in fact, there is a book: C. F. Martin Guitars, A History, by Mike Longworth. This book is a complete compendium of Martin history and manufacturing.

I hope this small amount of information helps eliminate some confusion when you are guitar shopping. At least until you hear “Gibson J-50, L-2, CF-100 . . . .”

Bob Smakula is a musician and resident of Randolph County, WV. He is the proprietor of Smakula Fretted Instruments, specializing in the restoration and sales of vintage stringed instruments. Email: bob@smakula.com

Thanks for the good info. I have an acoustic-electric Washburn and would like to upgrade to a Martin acoustic- electric. I just saw an ad from Guitar Center for a Martin D-14 acoustic-electric. I can find nothing about that guitar . . not even on the Martin website. If you know anything about the Martin D-14, I certainly would appreciate it.

This was the most helpful thing I have found…anywhere! I have a Martin 000C-16GTE that I purchased in high school (12 years ago). It is incredibly difficult to find any material about it. After lowering the action a little bit, I still haven’t found another Martin that I like. (Unless you get REALLY pricey)

Thanks for the info…been wearing my fingers out trying to understand this. I do have one question…My Martins model is JC – 16GTE
Based on your info the J stands for Jumbo and the ’16’ stands for the type of material it was made of….can you tell me what the “C” stands for and the “GTE” after the 16….thanks. I think this is a 2003 but not sure…is there somewhere that I can find that out?

Thanks – interesting to know – I’ve just bought a new OM21 which has an ebony fretboard and bridge so I guess Martin have reverted to the pre 50’s spec. combined with the modern performing artist profile neck – it really works – great to play and beautiful tone.

thanks. This was very helpful. I think your comment on the 17 is inaccurate though. The 17’s aren’t all mahogany (like the 15). They have mahogany back and sides, but a shaded Sitka spruce top (like the 16 and 18).

Hi,
I had a martinm104 guitar given to me as a teen in the late 1980’s (maybe). It was recently destroyed in a flooded basement but I can’t find any information on this model or what it all stands for. I would like information on replacement cost and where to get another, Could you help decode it for me or point me where I can find information on this guitar?
Thank you

Very nice article, thanks Bob. Wonder if there is a place for a quote to be added from this newly released article, by journalist Kent Priestley detailing Martin’s cultural legacy: https://www.americanmusical.com/Martin (scroll to bottom of page to read it now)

What are the differences between the parlor 2 1/2 17 compared to the parlor 2 1/2 18?
I heard one part was the 17 has the fan brace and the 18 is the x brace.
Thanks, just trying to confirm.
The year is 1895.